HomeMy WebLinkAboutIWA TOSW Pedestrian Bridge rvu 09-25-2023M E M O R A N D U M
To: South Windsor Inland Wetland/Conservation Commission.
From: Jeffrey H. Folger – Environmental Planner
Date: September 25, 2023
Re: Appl#23-39W Review of the proposed Town of South Windsor pedestrian bridge replacement site plan, 569 Griffin Road. Plans dated 09-2023.
The project is to re-construct a pedestrian span bridge on a 17.06-acre parcel. Disturbance within the Upland Review Area (URA) is estimated at 9390 sqft. Total direct impact is estimated
at 331 sqft.
Site: The site is located in the Podunk River watershed. The parcel contains Eli Terry Elementary School. The total land area equals approximately 17.06 acres. The specific site is
the old road right-of-way that extends from Griffin Rd to Brook St. The ROW was originally a possible future connection into the Brook St neighborhood that was never built.
Currently there exists an asphalt walking path over a 12-foot-long by 5-foot-wide span with headwalls. The project proposes to replace the existing span with a 19-foot-long by 11-foot-wide
span, and widen the approach asphalt path to 10 feet. Capable of allowing emergency vehicles access to the school and the playing field.
The site sits in a low point between two 8-foot slopes. The Podunk River channel being the low point. The channel is oriented east to west in this reach of the river and is a riffle-pool
configuration at the existing bridge. The watercourse channel at this point is approximately four to six feet wide, with an average depth of 6 inches at the riffle and 18 to 30 inches
at the pool area.
The main functions of the watercourse would be stormwater conveyance, groundwater surcharge, wildlife habitat, and fin-fish and shell-fish habitat.
Impacts:
The soils present on the site are mapped as Saco silt loam. This soil is hydric and common to flood plains. Erosion potential for activities on the site is expected to be low to moderate.
Coffer dams are proposed to sequester areas where work will be done within the channel. Perimeter silt fencing and follow-up slope stabilization will include rip-rap and grass seeding.
Stormwater:
The proposed wing walls will be located up to 10 feet wider that the current ones, which will allow for less restricted flow underneath the bridge. DEEP fisheries will be consulted
to determine the appropriate material to place in the channel bottom.